//
//  Copyright 2012, Xamarin Inc.
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;

using EmployeeDirectory.Core.Data;

namespace EmployeeDirectory
{
    public class MemoryDirectoryService : IDirectoryService
    {
        List<Person> people;

        Dictionary<string, PropertyInfo> properties;

        public MemoryDirectoryService(IEnumerable<Person> people)
        {
            this.people = people.ToList();
            this.properties = typeof(Person).GetRuntimeProperties().ToDictionary(p => p.Name);
        }

        #region IDirectoryService implementation

        public void Dispose()
        {
        }

        public Task LoginAsync(string username, string password, CancellationToken cancellationToken)
        {
            return Task.Factory.StartNew(() =>
            {
                //Just for testing
                //HACK: Thread.Sleep (2000);
            });
        }

        public Task<IList<Person>> SearchAsync(Filter filter, int sizeLimit, CancellationToken cancellationToken)
        {
            return Task.Factory.StartNew(() =>
            {
                var s = Search(filter);
                var list = s.ToList();
                return (IList<Person>)list;
            }, cancellationToken);
        }

        IEnumerable<Person> Search(Filter filter)
        {
            if (filter is OrFilter)
            {
                var f = (OrFilter)filter;
                var r = Enumerable.Empty<Person>();
                foreach (var sf in f.Filters)
                {
                    r = r.Concat(Search(sf));
                }
                return r.Distinct();
            }
            else if (filter is AndFilter)
            {
                throw new NotImplementedException();
            }
            else if (filter is NotFilter)
            {
                throw new NotImplementedException();
            }
            else if (filter is EqualsFilter)
            {
                var f = (EqualsFilter)filter;
                var upper = f.Value.ToUpperInvariant();
                var prop = properties[f.PropertyName];
                var q = from p in people
                        let v = prop.GetValue(p, null)
                        where v != null && v.ToString().ToUpperInvariant() == upper
                        select p;
                return q;
            }
            else if (filter is ContainsFilter)
            {
                var f = (ContainsFilter)filter;
                var re = new Regex(Regex.Escape(f.Value).Replace("\\ ", "|"), RegexOptions.IgnoreCase);
                var prop = properties[f.PropertyName];
                var q = from p in people
                        let v = prop.GetValue(p, null)
                        where v != null && re.IsMatch(v.ToString())
                        select p;
                return q;
            }
            else
            {
                throw new NotSupportedException("Unsupported filter type: " + filter.GetType());
            }
        }

        #endregion

        #region File IO

        public async static Task<MemoryDirectoryService> FromCsv(string path)
        {
            using var stream = await FileSystem.OpenAppPackageFileAsync(path);
            using var reader = new StreamReader(stream);
            return FromCsv(reader);
        }

        public static MemoryDirectoryService FromCsv(TextReader textReader)
        {
            var reader = new CsvReader<Person>(textReader);
            return new MemoryDirectoryService(reader.ReadAll());
        }

        #endregion
    }
}

